Lu Lu

Human infections with mpox virus (MPXV) since 2022 have resulted in more than 188,000 cases reported globally as of June 2026, highlighting the urgent need for effective therapeutics. Here, we recruited smallpox vaccinees and donors with incidental vaccinia virus (VACV) exposure and isolated a panel of human anti-A33/A35 monoclonal antibodies (mAbs) from the latter using recombinant MPXV A35 as a cross-reactive bait. These mAbs recognized four distinct nonoverlapping epitopes (epitopes 1 to 4) and one composite epitope (epitope 3 + 4) on MPXV A35 and exhibited cross-reactivity against multiple orthopoxviruses (OPXVs). Cryo–electron microscopy structural analysis revealed that the high-affinity epitope 3 + 4 mAb HD15 engages an epitope at the A35 dimer interface that is conserved across OPXVs. Combinations of mAbs targeting nonoverlapping epitopes mediated synergistic, Fc-dependent neutralization in vitro; conferred therapeutic protection against lethal VACV challenge; and reduced viral burden and disease severity after MPXV challenge in mice. Together, these findings establish a single-antigen, multiepitope strategy for the development of broadly protective therapeutics against OPXVs.

SUMMARY: Newly emerged highly pathogenic coronavirus species, including SARS-CoV, MERS-CoV, and SARS-CoV-2, have successively triggered outbreaks worldwide over the past 25 years. Recently, several MERS-related coronaviruses have been identified from bats or pangolins. These viruses, along with previously found SARS-related coronaviruses, pose significant potential to infect humans and trigger pandemics. Therefore, it is necessary to develop broad-spectrum vaccines that can combat both currently circulating coronaviruses and those that may emerge in the future. Currently, approved COVID-19 vaccines provide strong protection against pre-Omicron variants, while their effectiveness against post-Omicron variants is reduced, and cross-protection against other potential coronaviruses remains limited. In the present review, we discuss vaccine research on SARS-CoV and MERS-CoV prior to the COVID-19 outbreak, as well as vaccine development following the outbreak. We also focus on strategies for developing broad-spectrum coronavirus vaccines and provide a perspective on future directions for coronavirus vaccine development.

Overcoming immunosuppressive tumor microenvironments remains a critical challenge in advanced vaccine development. Here, we evaluated Pygenic acid A (PA), an intracellular small-molecule inhibitor targeting the PD-1/SHP-2 axis, as a novel vaccine adjuvant. The adjuvant efficacy of PA was systematically assessed in two murine models: a therapeutic B16-F10 melanoma lung metastasis model and a prophylactic lethal H1N1 influenza virus challenge model. In the melanoma metastasis model, PA potentiated the anti-tumor effect of the mTRP2 vaccine, markedly inhibiting pulmonary metastatic lesions and prolonging the survival of tumor-bearing mice. Mechanistically, PA robustly boosted the intratumoral infiltration of functional T cells, thereby reversing local tumor immunosuppression. In the influenza vaccination model, consistent immunostimulatory effects were observed: the PA-adjuvanted hemagglutinin (HA) vaccine effectively elicited broad-spectrum cross-neutralizing antibody responses and provided complete protection against lethal heterologous influenza virus challenge. Further mechanistic investigations demonstrated that PA specifically promoted the differentiation of T follicular helper (Tfh) cells and the expansion of germinal center (GC) B cells in draining lymph nodes, while triggering a robust Th1-type cellular immune response dominated by IFN-γ secretion. Furthermore, in vivo safety assessments verified that PA intervention induced no obvious systemic inflammation, hematological abnormalities, or visceral organ injury, indicating a favorable safety profile. Collectively, these results demonstrate that PA serves as a potent and safe intracellular checkpoint-targeting adjuvant capable of potentiating both cellular immunity and cross-protective humoral immunity, holding great translational promise for the development of advanced cancer vaccines and broad-spectrum influenza vaccines.

A major barrier in mucosal vaccine development is achieving localized immunity without systemic toxicity. Here we engineered NanoCF501, a nanoparticulate STING agonist formulated with a 2-ethyl-2-oxazoline polymer. As an adjuvant, NanoCF501 facilitates efficient mucus penetration and localized respiratory retention, minimizing systemic exposure as confirmed by pharmacokinetics in rats. In mice, intranasal co-administration of NanoCF501 (1/20th the systemic dose) with an antigen comprising multivalent fragments derived from different coronaviruses induced robust mucosal and systemic immunity, conferring protection against homologous/heterologous pan-β-coronaviruses. Single-cell transcriptomics reveals STING-dependent reprogramming of lung antigen-presenting cells, enhancing adaptive responses. Our results were further validated in non-human primates and were extended to licensed influenza vaccines, showing that NanoCF501 can be used to repurpose intramuscular antigens for mucosal delivery. By integrating nanoscale rational design with innate targeting, NanoCF501 establishes a universal adjuvant for next-generation vaccines, advancing nanomedicine for pandemic preparedness.

The continuous evolution of coronaviruses compromises the efficacy of existing therapeutic antibodies and replication inhibitors, necessitating antiviral strategies that are resilient to viral escape. Distinct from conventional antibody cocktails that remain vulnerable to spike protein mutations, we evaluated a multi-mechanistic therapy targeting three discrete stages of the viral life cycle: receptor binding, membrane fusion, and viral replication. Using pseudotyped and authentic human coronaviruses (HCoVs), including SARS-CoV-2 and HCoV-OC43, in cell culture models, we demonstrated that combining the pan-coronavirus fusion inhibitor EK1 with a receptor-binding domain-specific broadly neutralizing antibody (bnAb) and/or a main protease (M ^pro ) inhibitor yields synergistic inhibition. Collectively, our findings establish a conceptual framework for a trident antiviral regimen that theoretically restricts the evolutionary space for viral escape, although clinical translation will require optimizing delivery strategies to reconcile the distinct pharmacokinetic profiles of these agents. IMPORTANCE: The continuous emergence of highly transmissible and immune-evasive SARS-CoV-2 variants highlights an urgent need for broad-spectrum antiviral approaches capable of countering rapid viral evolution and future coronavirus outbreaks. Here, we designed a dual- or triple-stage antiviral strategy centered on the membrane fusion inhibitor EK1, in combination with a receptor-binding domain-targeting antibody and/or a small-molecule viral replication inhibitor (M ^pro inhibitor). In cell culture models, our results demonstrate marked synergy between EK1 and the antibody and/or the replication inhibitor. These combinations not only enhance antiviral potency but are also anticipated to maintain efficacy against emerging variants. By targeting non-overlapping stages of the viral life cycle, this approach theoretically raises the genetic barrier to resistance. While clinical translation will require reconciling the distinct pharmacokinetic profiles of these components, our study provides a conceptual framework for developing a trident anti-coronavirus therapy.

It remains elusive to design peptidomimetic inhibitors of SARS-CoV-2 main protease (M^pro) refractory to multiple deficiencies of Paxlovid (ritonavir-boosted nirmatrelvir), pertaining mainly to E166X mutations-conferred drug resistance and inherent pharmacokinetic limitations to nirmatrelvir. We identify via virtual screening an iso-quinoline P1 moiety in place of the traditional γ-lactam and design iso-quinoline-containing inhibitors with high affinity for M^pro and its nirmatrelvir-resistant E166X mutants. Further optimization at P4 cultivates distinctive peptidomimetic inhibitors with drastically improved pharmacokinetic properties and significantly enhanced antiviral efficacy independent of ritonavir. Two such inhibitors, FD3-32 and FD3-36, also potent against SARS-CoV-1 and MERS-CoV M^pro, are more effective as a monotherapy regimen than Paxlovid in reducing viral loads in vivo and protecting infected male mice from acute lung injury. Here, we report the discovery of next-generation SARS-CoV-2 M^pro inhibitors that overcome the deficiencies of Paxlovid, promising efficacious antivirals critical for mitigating the current and future pandemics of coronaviruses.